filter logging daemon
is a background daemon which reads packets
logged by pf(4)
, and writes the packets to a logfile
binary format. These
logs can be reviewed later using the -r
, hopefully offline
in case there are bugs in the packet parsing code of
closes and then re-opens the log file when
to flush the current logfile buffers to
the disk, thus making the most recent logs available. The buffers are also
flushed every delay
If the log file contains data after a restart or a
, new logs are appended to the
existing file. If the existing log file was created with a different snaplen,
temporarily uses the old snaplen to keep
the log file consistent.
tries to preserve the integrity of the log
file against I/O errors. Furthermore, integrity of an existing log file is
verified before appending. If there is an invalid log file or an I/O error,
the log file is moved out of the way and a new one is created. If a new file
cannot be created, logging is suspended until a
The options are as follows:
- Debugging mode. pflogd does
not disassociate from the controlling terminal.
- Time in seconds to delay between automatic flushes of the
file. This may be specified with a value between 5 and 3600 seconds. If
not specified, the default is 60 seconds.
- Log output filename. Default is
- Specifies the
pflog(4) interface to use. By
default, pflogd will use
- Analyze at most the first
snaplen bytes of data from each packet
rather than the default of 160. The default of 160 is adequate for IP,
ICMP, TCP, and UDP headers but may truncate protocol information for other
protocols. Other file parsers may desire a higher snaplen.
- Check the integrity of an existing log file, and
- Selects which packets will be dumped, using the regular
language of tcpdump(8).
Tcpdump has been extended to be able to filter on the pfloghdr structure
It can restrict the output to packets logged on a specified interface, a
rule number, a reason, a direction, an IP family or an action.
- Address family equals IPv4.
- Address family equals IPv6.
- ifname kue0
- Interface name equals "kue0".
- on kue0
- Interface name equals "kue0".
- ruleset authpf
- Ruleset name equals "authpf".
- rulenum 10
- Rule number equals 10.
- reason match
- Reason equals match. Also accepts
"bad-offset", "fragment", "short",
"normalize", "memory", "bad-timestamp",
"src-limit", and "synproxy".
- action pass
- Action equals pass. Also accepts "block" and
- The direction was inbound.
- The direction was outbound.
- Default log file.
Log specific TCP packets to a different log file with a large snaplen (useful
with a “log all” rule to dump complete sessions):
# pflogd -s 1600 -f suspicious.log port 80 and host evilhost
Log from another pflog(4)
interface, excluding specific packets:
# pflogd -i pflog3 -f network3.log "not (tcp and port 23)"
Display binary logs:
# tcpdump -n -e -ttt -r /var/log/pflog
Display the logs in real time (this does not interfere with the operation of
# tcpdump -n -e -ttt -i pflog0
Display the logs in real time of inbound packets that were blocked on the wi0
# tcpdump -n -e -ttt -i pflog0 inbound and action block and on wi0
command appeared in
was written by
Can Erkin Acar